Fluoropolymers commonly have one or more thermally unstable terminal groups other than —CF3, such as —COF, —COOH, —CH2OH, and —COOCH3, because of the polymerization mechanisms thereof though it depends, for example, on the polymerization initiator species and chain transfer agent species used in polymerization of the fluoropolymers. Such terminal groups in fluoropolymers may cause foaming or generation of hydrofluoric acid during molding, which may lead to a failure in molding or to mold corrosion.
Patent Document 1 discloses a method of fluorinative decomposition of polytetrafluoroethylene in which fluorinative decomposition is carried out in the presence of an alkali metal fluoride and/or an alkali earth metal fluoride. In addition, Non Patent Document 1 discloses a process including the step of mixing polyethylene with potassium fluoride followed by a fluorine flow through a reactor.    Patent Document 1: JP-A H1-180839    Non Patent Document 1: POLYMER LETTERS EDITION, VOL. 12, PP. 177-184 (1974)